{"id":71639,"date":"2020-01-10T16:00:14","date_gmt":"2020-01-10T10:30:14","guid":{"rendered":"https:\/\/www.vskills.in\/certification\/tutorial\/?p=71639"},"modified":"2024-04-12T14:22:36","modified_gmt":"2024-04-12T08:52:36","slug":"typescript-features-2","status":"publish","type":"page","link":"https:\/\/www.vskills.in\/certification\/tutorial\/typescript-features-2\/","title":{"rendered":"TypeScript Features"},"content":{"rendered":"\n<p><a href=\"https:\/\/www.vskills.in\/certification\/tutorial\/angular-7-developer-tutorials\/\" target=\"_blank\" rel=\"noreferrer noopener\">Go back to Tutorial<\/a><\/p>\n\n\n<p>Now that producing JavaScript from TypeScript code has been de-mystified, some of its features can be described and experimented with.<\/p>\n<ul>\n<li>Types<\/li>\n<li>Interfaces<\/li>\n<li>Shapes<\/li>\n<li>Decorators<\/li>\n<\/ul>\n<h4>Types<\/h4>\n<p>Many people do not realize it, but JavaScript does in fact have types, they&#8217;re just &#8220;duck typed&#8221;, which roughly means that the programmer does not have to think about them. JavaScript&#8217;s types also exist in TypeScript:<\/p>\n<ul>\n<li>boolean (true\/false)<\/li>\n<li>number integers, floats, Infinity and NaN<\/li>\n<li>string characters and strings of characters<\/li>\n<li>[] Arrays of other types, like number[] or boolean[]<\/li>\n<li>{} Object literal<\/li>\n<li>undefined not set<\/li>\n<\/ul>\n<p>TypeScript also adds<\/p>\n<ul>\n<li>enum enumerations like { Red, Blue, Green }<\/li>\n<li>any use any type<\/li>\n<li>void nothing<\/li>\n<\/ul>\n<p><u>Primitive type example:<\/u><\/p>\n<p>let isDone: boolean = false;<\/p>\n<p>let height: number = 6;<\/p>\n<p>let name: string = &#8220;bob&#8221;;<\/p>\n<p>let list: number[] = [1, 2, 3];<\/p>\n<p>let list: Array&lt;number&gt; = [1, 2, 3];<\/p>\n<p>enum Color {Red, Green, Blue};<\/p>\n<p>let c: Color = Color.Green;<\/p>\n<p>let notSure: any = 4;<\/p>\n<p>notSure = &#8220;maybe a string instead&#8221;;<\/p>\n<p>notSure = false; \/\/ okay, definitely a boolean<\/p>\n<p>function showMessage(data: string): void {<\/p>\n<p>alert(data);<\/p>\n<p>}<\/p>\n<p>showMessage(&#8216;hello&#8217;);<\/p>\n<p>This illustrates the primitive types in TypeScript, and ends by illustrating a showMessage function. In this function the parameters have specific types that are checked when tsc is run.<\/p>\n<p>In many JavaScript functions it&#8217;s quite common for functions to take optional parameters. TypeScript provides support for this, like so:<\/p>\n<p>function logMessage(message: string, isDebug?: boolean) {<\/p>\n<p>if (isDebug) {<\/p>\n<p>console.log(&#8216;Debug: &#8216; + message);<\/p>\n<p>} else {<\/p>\n<p>console.log(message);<\/p>\n<p>}<\/p>\n<p>}<\/p>\n<p>logMessage(&#8216;hi&#8217;);&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; \/\/ &#8216;hi&#8217;<\/p>\n<p>logMessage(&#8216;test&#8217;, true); \/\/ &#8216;Debug: test&#8217;<\/p>\n<p>Using a ? lets tsc know that isDebug is an optional parameter. tsc will not complain if isDebug is omitted.<\/p>\n\n\n<p><a href=\"https:\/\/www.vskills.in\/certification\/tutorial\/angular-7-developer-tutorials\/\" target=\"_blank\" rel=\"noreferrer noopener\">Go back to Tutorial<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"<p>Go back to Tutorial Now that producing JavaScript from TypeScript code has been de-mystified, some of its features can be described and experimented with. Types Interfaces Shapes Decorators Types Many people do not realize it, but JavaScript does in fact have types, they&#8217;re just &#8220;duck typed&#8221;, which roughly means that the programmer does not have&#8230;<\/p>\n","protected":false},"author":1,"featured_media":0,"parent":0,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"footnotes":""},"categories":[8294],"tags":[7283],"class_list":["post-71639","page","type-page","status-publish","hentry","category-angular-7","tag-typescript-features"],"acf":[],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v24.5 - https:\/\/yoast.com\/wordpress\/plugins\/seo\/ -->\n<title>TypeScript Features - Tutorial<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/www.vskills.in\/certification\/tutorial\/typescript-features-2\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"TypeScript Features - Tutorial\" \/>\n<meta property=\"og:description\" content=\"Go back to Tutorial Now that producing JavaScript from TypeScript code has been de-mystified, some of its features can be described and experimented with. 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